They order them from a company in China just like everybody else does. Hell they are probably assembling Sony Viao batteries on the next table, except they are calling the Lithium Polymer technology something else.
Also on any full sized laptop with a 13 inch or larger screen, dual core CPU and a heavy weight video processor the only way you are going to get more than 4 to 5 hours uptime is to leave the screen virtually dark, WiFi off, Bluetooth Off, do not touch the keyboard or touch pad, and do not run any programming other than the OS.
However if you need a higher output spare battery at half the price go to
http://www.mambate.com/Apple They have very high quality replacement units and if you need an in-car charger for your Mac this unit is a universal charger that might work for you and it is $34.95.
http://www.mambate.com/Items/ap61?&caSKU=ap61&caTitle=Universal%20Laptop%20Notebook%20DC%20CAR%20Charger%20Power%20Adapter%20-%20SKU%3a%20AP61 This company has quick service and very low shipping and handling.